Arcing horn for circuit interrupter



April 22, 1958 w. B. KELLY ARCING HORN FOR CIRCUIT INTRRRURTRR Filed May 14, 1954 ETE- E.

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.n d TME \N CYCLES Y ARCIN G HQRN FOR CBRCUIT INTERRUPTER Walter B. Kelly, New Stanton, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 1.4, 1954, SerialNo. 429,873 Claims. (Cl. 20d- 48) This invention relates to circuit interrupters and more particularly to arcing horns for use in conjunction with open air type switches.

One or" the highly important features of an arcing horn is the speed with which it breaks contact. Thus, the degree of arcing is inversely proportional to the speed with which the moving contact leaves the stationary contact and maintains a traverse away from the stationary contact. In general, it is necessary for the moving horn to acquire as fast a speed as possible in as short a time as possible from the instant or disengaging the stationary arc horn in order to minimize the length and intensity of the ensuing arc.

Accordingly, it is the primary object of the invention to provide an arcing horn capable of high acceleration at the instant of release and of high speed throughout the path of travel.

It is another object of the invention to provide a horn construction of great simplicity which can be easily manufactured and readily adapted for use in conjunction with a number `of types of switches. i

In general, my invention comprises the use of a tapered, tubular element for the movable horn which element is preferably, though not necessarily, made of beryllium copper tubing. I have found that such a construction lends itself readily to my particular purpose and results in a flexible horn having a whip-like action wherein the tip of the horn attains speeds substantially in excess of those heretofore effected by prior arcing horns.

` Thus, after a degree of iiexing until the trip of the horn leaves the stationary contact member, the horn snaps out at a high speed away from the stationary member. I have found that such speeds are of the order of 90 feet per second at the horn tip and by virtue of that high speed, contact is broken in practically all cases with no visible arc between the movable horn tip and the stationary horn.

The speeds utilized for test purposes under actual operating conditions are found to be in excess of l5 per cycle in a 60 cycle line. For example, an arcing horn arrangement as disclosed herein was successfully used on a 20,000 kva. bank 'of transformers at 69 kv. to interrupt the magnetizing current with no visible arcing.

In fact, tests have shown that the horn of the invention has an accelerating time of only 0.2 of a cycle from the instant the tip of the movable contact leaves the stationary arc horn until constant speed is achieved throughout the remainder of the opening stroke.

This extremely high speed provided by so short an accelerating period is believed to be the reason for the superior performance of my device. Further, I have found that where the horn tip moves at a speed of approximately l5" per cycle and above, little or no visible arcing is obtained.

Thus, my invention effects, for the first time, an extremely high speed movable horn element which attains a practically constant speed almost instantly after the horn tip leaves the stationary contact, producing a highly desirable and unexpected effect to the extent of eliminating visible arcing, an effect not hitherto achieved by the prior art.

A detailed description of my invention will now be given in conjunction with the appended drawing, in which:

Figure 1 is a plan view showing my invention as applied rates Patent() N ice to a conventional type of switch illustrating the position of the parts when the switch is closed. The dotted portion illustrates the position of the components when the switch blade is open but before the moving arc horn leaves the stationary arc horn.

Figure 2 is an elevation View of the switch set forth in Figure 1.

Figure 3 is an elevation of the stationary element of the arcing horn.

Figure 4a is a detailed illustration of the movable arc horn.

Figure 4b is a modiiied version of the movable arc horn.

Figure 5 is a graph showing the horn tip travel in feet as compared with time in cycles.

With reference to the drawings, the invention comprises a tubular, tapering horn element 10 having one end suitably fastened as by a clamp 12 to a pedestal 14 which, in turn, is clamped to the movable blade 18 of a, conventional type of outdoor switch.

Thus, the larger diameter left end of arc horn 10 is securely fastened to blade 18 while the outer and smaller right end is disposed within the contines of the angle 22 of a stationary arc horn 24. The arc horn 24 is the stationary member of the horn arrangement and is securely attached to the stationary contact 26 of the switch.

A reinforcing sleeve 27 may be placed in the end of horn 10 to withstand the compression of clamp 12, an opening 30 in the sleeve being utilized to serve as a drain.

Accordingly, it will be appreciated that when the switch is opened, for example, blade 18 moving clockwise, as seen on Figure 1, moving arc horn 10 will electrically engage the stationary arc horn 24 in the vertex of the angle 22 and will be ilexed as shown by the dotted lines in Figure 1. Thus, as the switch contacts are being opened, arc horn 10 and 24 remain in contact until such time as the tip of element 10 slides past the vertex of the angle 22. At this instant, element 10, by virtue of its novel construction, straightens out with an extremely rapid, whip-like action, thereby attenuating the arc which would otherwise occur and, accordingly, the current controlled by the switch is completely cut otl with no visible arcing or other damaging effect, owing to the high speed of exure of the element 10.

The details of the movable arc horn 10 are shown in Figure 4a wherein such element is seen to consist of a` tapered horn whichis tubular and which has a wall thickness which may vary from 0.005" to 0.150. The rod as shown in Figure 4a is of stepped construction but it could be smoothly tapered from one end to the other as shown in Figure 4b.

In the course of many experiments, l have constructed arcing horns such as 10 in various lengths for various types -of switches and have successfully operated arcing horns wherein the arc horn length has been varied from 131/2 to 58". The degree of taper varied from 0.150 at the larger end to 0.115 at the outer tip for a horn 131/2" long, to 0.562" at the larger end and 0.270 at the smaller end for a horn 58 long. Such horns were constructed of hard beryllium copper; however, other metals such as stainless steel are believed to be suitable.

Specilcally, I have constructed successfully operable horns having the following dimensions, given in inches:

aesinet These rods had approximately 2" st'eps and the thickness of material varied from 0.015 to 0.020". The above noted dimensions are representative of a few of the tested arcing horns incorporating my invention and does not include all of the variety of combinations of dimensions which may be used in accordance with my disclosure.

Figure 5 shows a generalization of horn-tip travel in feet as compared with cycle time.` For example, it will be seen that a horn constructed in accordance withl my invention has a tip travel of 1 foot in about 3A of a cycle, this being for the usual 60 cycle current. At the end of one cycle, the rod tip will have moved about 17 Thus, the actual speed approaches 90 feet per second although contact is fully and safely broken after some 0.2 of a cycle has elapsed at which time the horn tip is travelling at substantially constant speed for the remainder of its stroke, that is, about 90 feet per second.

From the foregoing, it will be apparent that various changes may be made within the spirit of the invention. However, I believe that the use of a tubular, tapered horn as generally described will produce the phenomenal high speed interrupting effect as set forth above, and accordingly, l do not seek to Ibe limited to the precise illustration herein given except as set forth in the appended claims.

l claim:

1. A quick break arc horn for a switch having a iirst and second member; said switch members having an engaged, intermediate and disengaged position with respect to each other; said quick break arc horn having one end larger than the other; the larger end of said arc horn secured to one of said switch members; said arc horn being exed by the movement of said switch members from said engaged position to said intermediate position to thereby store energy therein; said arc horny releasing said stored energy to etfect an electrical quick break between said switch members when they are moved from said intermediate position to said disengaged position; said quick break 'arc horn comprised of an elongated hollow tubular member tapered from one end to the other.

2. A quick break arc horn for a switch having a rst and second member; said switch members having an engaged, intermediate and disengaged position with respect to each other; said quick break arc horn having one end larger than the other; the larger end of said arc horn secured tov one of said switch members; said arc horn being flexed by the movement of'said switch members from said engaged position to said intermediate position to thereby store energy therein; said arc horn releasing said stored energy to eiect an electrical quick break between said switch members when they are moved from said intermediate position to said disengaged position; said quick break' arc horn comprising an elongated hollow tubular member tapered in a plurality of steps from one end to the other.

3. A quick break 'arc horn for a switch having a rst and second member; said switch members having an ngaged, intermediate and disengaged position with respect to each other; said quick break arc horn having one end larger than the other; the larger end of said arc horn secured to one of said switch members; said arc horn being flexed by the movement oi said switch members from said engaged position to said intermediate position to thereby store energy therein; said arc horn releasing said stored energy to eiect an electrical quick break between said switch members when they are moved from said intermediateA position to said disengaged position; said quick break arc horn comprising an elongated hollow tubular member tapered from one end to the other with the diameter of said larger end being from two to six times the diameter of the other end.

4. A quick break arc horn for a switch having a first and second member; Said switch members having an engag'ed', intermediate and disengaged position with respect to each other; said quick break arc horn having one e'nd larger than the other; the larger end of said arc horn secured t'o one of said switch members; said arc horn being flexed by the movement of said switch members from said engaged position to said intermediate position to thereby store energy therein; said arc horn releasing said stored energy to effect an electrical quick break between said switch members when they are moved from Said intermediate position to said disengaged position; said quick break arc horn comprising an elongated hollow tubular member tapered from one end to the other and having a wall thickness between 0.005 and 0.150".

5. A quick break arc horn for a switch having a' first and second member; said switch members having an engaged, intermediate and disengaged position with respect' to each other; said quick break arc horn having one end larger thanl the other; the larger end of said arc horn secured to one' of said switch members; said arc horn being flexed bythe movement of said switch membersfrom said engaged position to said intermediate position to thereby store energy therein; said arc horn releasing said stored energy to effect an electrical quick break between said switch members when they are moved from' said intermediate position to said disengaged position; said quick break' arc horn comprising an elongated hollowv tubular member of beryllium copper tapered in a plurality of steps from one end to the other with the diameter of said larger` end being from two to six timesv the diameter of the other end and having a wall thickness between 0.005 and 0.150.

References Cited in the tile of this patent UNITED STATES PATENTS 1,230,372 Bowie June 19,- 1917 1,919,065 Jacobs 1 July 18, 1933 2,317,118 Schultz et al. Apr. 20, 1943 2,727,105 Turner Dec. 13, 1955 

